1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2018 The FreeBSD Foundation
5 *
6 * This software was developed by Mark Johnston under sponsorship from
7 * the FreeBSD Foundation.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions are
11 * met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in
16 * the documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33
34 #include <sys/types.h>
35 #include <sys/capsicum.h>
36 #include <sys/dnv.h>
37 #include <sys/nv.h>
38 #include <sys/queue.h>
39 #include <sys/wait.h>
40
41 #include <net/if.h>
42 #include <netinet/in.h>
43
44 #include <capsicum_helpers.h>
45 #include <errno.h>
46 #include <stdlib.h>
47 #include <string.h>
48 #include <unistd.h>
49
50 #include <libcasper.h>
51 #include <libcasper_service.h>
52
53 #include "rtsold.h"
54
55 /*
56 * Run the script and return the write end of a pipe to the main process.
57 * Return -1 and set errno on error.
58 */
59 static int
script_run(char ** argv)60 script_run(char **argv)
61 {
62 pid_t pid;
63 int fd[2], null;
64
65 if (pipe(fd) != 0)
66 return (-1);
67 if ((pid = fork()) < 0)
68 return (-1);
69 if (pid == 0) {
70 (void)close(fd[1]);
71 null = open("/dev/null", O_RDWR);
72 if (null < 0)
73 _exit(1);
74 if (dup2(fd[0], STDIN_FILENO) != STDIN_FILENO)
75 _exit(1);
76
77 closefrom(3);
78 (void)execve(argv[0], argv, NULL);
79 _exit(1);
80 } else
81 (void)close(fd[0]);
82
83 return (fd[1]);
84 }
85
86 int
cap_script_run(cap_channel_t * cap,const char * const * argv)87 cap_script_run(cap_channel_t *cap, const char *const *argv)
88 {
89 #ifdef WITH_CASPER
90 nvlist_t *nvl;
91 size_t argc;
92 int error, wfd;
93
94 for (argc = 0; argv[argc] != NULL; argc++)
95 ;
96
97 nvl = nvlist_create(0);
98 nvlist_add_string(nvl, "cmd", "script_run");
99 nvlist_add_string_array(nvl, "argv", argv, argc);
100 nvl = cap_xfer_nvlist(cap, nvl);
101 if (nvl == NULL)
102 return (-1);
103
104 error = (int)dnvlist_get_number(nvl, "error", 0);
105 if (error == 0)
106 wfd = nvlist_take_descriptor(nvl, "fd");
107 nvlist_destroy(nvl);
108 if (error != 0)
109 errno = error;
110 return (error == 0 ? wfd : -1);
111 #else
112 (void)cap;
113 return (script_run(__DECONST(char **, argv)));
114 #endif
115 }
116
117 /*
118 * Wait for a child process to exit, and return its status.
119 * Return -1 and set errno upon error.
120 */
121 static int
script_wait(int * statusp)122 script_wait(int *statusp)
123 {
124 int error;
125
126 error = wait(statusp);
127 return (error >= 0 ? 0 : -1);
128 }
129
130 int
cap_script_wait(cap_channel_t * cap,int * statusp)131 cap_script_wait(cap_channel_t *cap, int *statusp)
132 {
133 #ifdef WITH_CASPER
134 nvlist_t *nvl;
135 int error;
136
137 nvl = nvlist_create(0);
138 nvlist_add_string(nvl, "cmd", "script_wait");
139 nvl = cap_xfer_nvlist(cap, nvl);
140 if (nvl == NULL)
141 return (-1);
142
143 error = (int)dnvlist_get_number(nvl, "error", 0);
144 if (error == 0)
145 *statusp = (int)nvlist_get_number(nvl, "status");
146 nvlist_destroy(nvl);
147 if (error != 0)
148 errno = error;
149 return (error == 0 ? 0 : -1);
150 #else
151 (void)cap;
152 return (script_wait(statusp));
153 #endif
154 }
155
156 #ifdef WITH_CASPER
157 static int
script_command(const char * cmd,const nvlist_t * limits,nvlist_t * nvlin,nvlist_t * nvlout)158 script_command(const char *cmd, const nvlist_t *limits, nvlist_t *nvlin,
159 nvlist_t *nvlout)
160 {
161 cap_rights_t rights;
162 const char *const *iargv, *const *scripts;
163 char **argv;
164 size_t argc, i, nscripts;
165 int error, fd, status;
166
167 if (strcmp(cmd, "script_wait") == 0) {
168 /* Wait for the result of a previous "script_run" command. */
169 if (script_wait(&status) == -1)
170 return (errno);
171 nvlist_add_number(nvlout, "status", status);
172 return (0);
173 }
174 if (strcmp(cmd, "script_run") != 0)
175 return (EINVAL);
176
177 /*
178 * Validate the argv against the limits specified at initialization
179 * time.
180 */
181 iargv = nvlist_get_string_array(nvlin, "argv", &argc);
182 if (argc == 0)
183 return (EINVAL);
184 scripts = nvlist_get_string_array(limits, "scripts", &nscripts);
185 for (i = 0; i < nscripts; i++)
186 if (strcmp(iargv[0], scripts[i]) == 0)
187 break;
188 if (i == nscripts)
189 return (EINVAL);
190
191 /*
192 * The nvlist API does not permit NULL pointers in an array, so we have
193 * to add the nul terminator ourselves. Yuck.
194 */
195 argv = calloc(argc + 1, sizeof(*argv));
196 if (argv == NULL)
197 return (errno);
198 memcpy(argv, iargv, sizeof(*argv) * argc);
199
200 fd = script_run(argv);
201 error = errno;
202 free(argv);
203 if (fd < 0)
204 return (error);
205
206 (void)caph_rights_limit(fd, cap_rights_init(&rights, CAP_WRITE));
207 nvlist_move_descriptor(nvlout, "fd", fd);
208 return (0);
209 }
210
211 static int
script_limit(const nvlist_t * oldlimits,const nvlist_t * newlimits)212 script_limit(const nvlist_t *oldlimits, const nvlist_t *newlimits)
213 {
214 const char *name;
215 void *cookie;
216 int nvtype;
217 bool hasscripts;
218
219 /* Limits may only be set once. */
220 if (oldlimits != NULL)
221 return (ENOTCAPABLE);
222
223 cookie = NULL;
224 hasscripts = false;
225 while ((name = nvlist_next(newlimits, &nvtype, &cookie)) != NULL) {
226 if (nvtype == NV_TYPE_STRING_ARRAY &&
227 strcmp(name, "scripts") == 0)
228 hasscripts = true;
229 else
230 return (EINVAL);
231 }
232 if (!hasscripts)
233 return (EINVAL);
234 return (0);
235 }
236
237 CREATE_SERVICE("rtsold.script", script_limit, script_command, 0);
238 #endif /* WITH_CASPER */
239